Anti-flooding efforts carried out by city authorities have seen significant improvements including a reduction in the number of flood-prone areas as well as the severity of the flooding, Vu Van Diep, director of the HCMC Infrastructure Management Center under the Department of Construction, said Tuesday.

Not only the number of flood-prone areas in the city has reduced, the flooding period has been shortened from four to six hours to 15-40 minutes after the rain stops, he said at a press meet.

Since the beginning of the rainy season last month, the city has suffered from three heavy downpours with rainfall ranging from 70 to 112 mm that have exceeded the capacity of the water drainage system, causing flooding in 22 streets.

Among the current flood-prone areas are Nguyen Huu Canh Street in Binh Thanh District, Nguyen Van Huong and Quoc Huong Streets in District 2's Thao Dien area, home to a large expat community, and some streets in Thu Duc, Go Vap and Binh Tan Districts.

Diep said flooding in the city was mainly caused by the outdated drainage system and waterway encroachment.

Over the past five years, HCMC has invested nearly VND26 trillion ($1.12 billion) on anti-flooding projects, including a VND10 trillion ($432 million) project that covers 100 hectares (250 acres) in Districts 1, 4, 7, 8, Binh Chanh and Nha Be.

The long-delayed project, which started in 2016, is expected to be completed in October 2020.

Nguyen Huu Canh Street, which connects the downtown District 1 with District 2 and is notorious for frequent flooding, is being upgraded with another VND473 billion ($20.4 million) project that is expected to be completed in April 2021.

Built in 1997 and opened to traffic in 2002, the VND420 billion ($18 million) Nguyen Huu Canh Street had carried high hopes of improving traffic flow in HCMC.

But soon after it opened, the street that spans 3.2 km subsided and began getting inundated every time it rains.

Le Hoa Binh, director of municipal construction department, said the city still faces challenges to its flood-prevention efforts, such as rapid urbanization, continuing subsidence and, in particular, climate change.

Flooding risks in HCMC may grow 10 times more intense by 2050 given the current prevalence of poorly regulated construction projects and economic activities, according to a recent study by international consulting firm McKinsey.

It said the city may lose billions of dollars as sea levels rise and a majority of its area may become vulnerable to extreme weather events without serious adaptation and systemic reform of urban planning, it warned.